Snowmobile slide rail system

ABSTRACT

A slide rail system of a snowmobile vehicle includes a pair of substantially parallel elongated front slide rails, each front slide rail having a forward end and a rear end, the forward end pivotally connected to a chassis or a front drive axle of the snowmobile. The system also includes a pair of substantially parallel elongated rear slide rails, each rear slide rail having a forward end pivotally connected to the rear end of each front slide rail.

[0001] This application is a Divisional of U.S. Utility patentapplication Ser. No. 10/141,855, filed on May 10, 2002, which is acontinuation of U.S. Utility patent application Ser. No. 10/082,349,filed Feb. 26, 2002, which is incorporated herein by reference. Throughapplication Ser. No. 10/082,349, this application claims furtherpriority to U.S. Provisional Patent Application No. 60/270,879, filedFeb. 26, 2001, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] This invention relates to suspension systems for trackedvehicles, and, more specifically, to a slide rail system for asnowmobile.

BACKGROUND OF THE INVENTION

[0003] Generally, suspension systems are very heavy and bulky due totheir complexity and the number of parts required. As illustrated inFIGS. 1 and 2, most suspension systems require a pair of elongated sliderails 1 that are curved at their forward end 2 to follow an endlesstrack 3. Front and rear suspension arms 4, 5 link the slide rails 1 andthe chassis 6 of the snowmobile 7 together. The front and rearsuspension arms 4, 5, together along with the chassis 6 and the sliderails 1, form a parallelogram structure.

[0004] One aspect that all prior art suspension systems have in commonis the shape of the slide rails 1. Slide rails 1 have generally beenstructured to include a flat surface 8 toward the rear end of the sliderail 1, which slides along an endless track parallel with the ground.The forward end 2 of the slide rails 1 curves or angles towards thechassis 6 to create an angle of attack □ of the track 3. Another aspectthat is common to the prior art slide rails is an unsupported frontportion of the track between the front drive axle and the forward end 2of the slide rails.

[0005] The distance needed to ensure the minimum amount of tractionbetween the snowmobile track 3 and the ground determines the minimumlength of the rear flat surface 8.

[0006] Several suspension designs appear in the prior art, a few ofwhich are described briefly below.

[0007] U.S. Pat. No. 5,860,486, incorporated herein by reference,describes a suspension system comprising a single, generally centrallymounted structure in a middle portion of the rear suspension system. Thesuspension system comprises a pair of inclined primary suspensionnumbers and a pair of inclined primary oscillating arms pivotallyconnected to a pair of longitudinal slide rails. U.S. Pat. No. 5,860,486describes one central suspension arm. Shock absorbers provide for asecond attachment between the slide rails and the chassis. Specifically,because of this design, the slide rails do not extend all the way to theforward drive axle, thus creating a space where the track fails tocontact the slide rails, which adversely effects snowmobile performancein soft snow.

[0008] U.S. Pat. No. 5,033,572, incorporated herein by reference,describes a suspension system having a pair of slide rails, whichincorporate two angles of attack. One of the angles of attack favorstrail riding while the other provides necessary traction in deeper snow.

[0009] U.S. Pat. No. 5,904,216, incorporated herein by reference,describes a suspension system that provides a compact assembly and yetpermits the use of a single cushioning unit that extends horizontallywithin the frame to provide large suspension travel in a relativelysmall area.

[0010] While these designs offer certain advantages, they also sufferfrom certain drawbacks, which result from reliance on the traditionalslide rail as the primary element of the suspension. One specificdrawback of conventional slide rails system is the need of front andrear suspension arms that attach the slide rails to the chassis. Theneed of two suspension arms renders the conventional suspension systemsheavy and bulky. A second drawback is the unsupported front portion ofthe track between the front drive axle and the forward end of the sliderails. This unsupported portion of the track tends to cave inwards dueto the pressure of the snow thus creating a lump of snow which the sliderails must travel over or push through, preventing the track from ridingon the top surface of the snow.

SUMMARY OF THE INVENTION

[0011] There is a need for a new and improved slide rails system thatoffers an improved construction to avoid, or at least lessen, the effectof the drawbacks described above.

[0012] It is an object of the present invention to provide a new sliderail system with improved characteristics that will help decrease theweight and cost of the entire suspension system, provide greater supportfor the track, and create an improved angle of attack for the track.

[0013] It is another object of the present invention to provide a sliderail system, which includes a pair of parallel elongated front sliderails attached together with a series of transverse bars pivotallyattached to a second pair of parallel rear slide rails attached togetherwith a series of transverse bars. The forward end portions on the frontslide rails are pivotally attached to the chassis of a snowmobile nearthe front drive sprocket thereby providing support for the entireportion of the track engaging with the terrain over which the vehicle isdriven.

[0014] Still another object of the present invention is to provide aslide rail system where the front slide rails are attached to thechassis through a linkage member.

[0015] Still another object of the present invention is to provide aslide rail system where the front slide rails are directly attached tothe front drive axle of a snowmobile.

[0016] Another object of the present invention is to provide a sliderail system where the ratio between the length of the front slide railsand the rear slide rails is between 50% and 100%.

[0017] Yet another object of the present invention is to provide a sliderail system where the pivot point between the front and rear slide railsis situated a predetermined distance from the drive axle of thesnowmobile.

[0018] It is still another object of the present invention to provide aslide rail system where the pivot point between the front slide railsand the chassis is a predetermined distance from the front drive axle ofthe snowmobile.

[0019] It is yet another object of the present invention to provide asuspension system where the slide rails include a pair of front and rearslide rails. The front and rear slide rails are pivotally connected toone another. The front slide rails are also adapted to be pivotallyconnected to the chassis near the front drive axle. The suspensionsystem includes at least one suspension arm attaching one of the rearslide rails and the front slide rails to the chassis and one shockassembly attaching one of the front slide rails and the rear slide railsto the chassis of the snowmobile.

[0020] According to another aspect of the present invention, asnowmobile is provided that includes a chassis. An engine is disposed onthe chassis. A steering column is attached to at least one ski forsteering the snowmobile over the snow. An endless track is disposedunder the chassis and is operatively connected to the engine forpropelling the snowmobile. The snowmobile includes a slide rail system,which includes a pair of parallel elongated front slide rails attachedtogether with at least one transverse bar pivotally attached to a secondpair of parallel rear slide rails also attached together with transversebars. The front-end portions of the front slide rails are pivotallyattached to one of the chassis of a snowmobile near the front drive axleor directly to the front drive axle.

[0021] Another object of the present invention is to provide asnowmobile with a suspension system that includes a pair of front andrear slide rails which pivot with respect to one another. The suspensionsystem includes at least one suspension arm attaching one of the frontslide rails and the rear slide rails to the chassis and one shockassembly attaching one of the front slide rails and the rear slide railsto the chassis of the snowmobile.

[0022] Yet another object of the present invention is to provide theslide rail system with a mechanism that will prevent the rotation of therear suspension arm such that the weight transfer of the vehicle will becontrollable.

[0023] Still another object of the present invention is to provide asnowmobile with a suspension system in which the ratio of the length ofthe endless track to the length of the rear slide rails is apredetermined number.

[0024] It is still another object of the present invention to provide asnowmobile with a suspension system in which the ratio of the length ofthe endless track to the length of the front slide rails is apredetermined number.

[0025] The foregoing objects are not meant to limit the scope of thepresent invention. To the contrary, still other objects of the presentinvention will become apparent from the description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Reference will be made hereinafter to the accompanying drawings,which illustrate embodiments of the present invention discussed hereinbelow, wherein;

[0027]FIG. 1 is a side elevation view of the prior art snowmobile withthe suspension system shown in solid lines;

[0028]FIG. 2 is a side elevation view of a prior art slide rail systemshown in FIG. 1;

[0029]FIG. 3 is a left rear perspective view of a first embodiment ofthe slide rail system according to the present invention;

[0030]FIG. 4 is a left side view of the first embodiment of thesuspension system of the present invention;

[0031]FIG. 5 is a perspective view of a prior art rear suspension systemsupported by the slide rail system of the present invention;

[0032]FIG. 6 is a left side view of a prior art rear suspension systemsupported by the slide rail system of the present invention;

[0033]FIG. 7 is a left side view of a second embodiment of the sliderail system of the present invention supporting a prior art cushioningunit;

[0034]FIG. 8 is a top cross-section of a first pivot connection betweenthe front and rear slide rails;

[0035]FIG. 9 is a partially exploded perspective view of the pivotconnection between the front and rear slide rails shown in FIG. 8;

[0036]FIG. 10 is an alternate pivot connection between the front andrear slide rails;

[0037]FIG. 11 is top cross-section of a pivot connection between thefront slide rails and the chassis.

[0038]FIG. 12 is left side view of a snowmobile equipped with a sliderail system of the present invention;

[0039]FIG. 13 is a left side view of a third embodiment of the sliderail system of the present invention supporting a prior art cushioningunit;

[0040]FIG. 14 is a top cross-section of a pivot connection between thefront slide rails and the front drive axle;

[0041]FIG. 15 is a top view of an alternate pivot connection between thefront slide rails and the front drive axle;

[0042]FIG. 16 is a perspective view of a fourth embodiment of the sliderail system of the present invention; and

[0043]FIG. 17 is a partial side view of the embodiment shown in FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] A slide rail system 10 according to the present invention isshown in FIGS. 3-17. The slide rail system 10 shown in FIG. 3 has rearslides rails 12 and front slide rails 14. The front slide rails 14 arepivotally attached to rear slide rails 12 at a pivot point 26.

[0045] Rear slide rails 12 include a right slide rail 16 and a leftslide rail 18. Front slide rails 14 have a right slide rail 20 and aleft slide rail 22. (The “right” and “left” sides are defined withreference to the forward travel direction of the snowmobile).

[0046] As shown in FIG. 3, the rear slide rails 12 have a forward end28, which is pivotally attached to the rear end 30 of the front sliderails 14. The front slide rails 14 also have a forward end 32, which ispivotally attached to the chassis 34 by linkages 50.

[0047] Front and rear slide rails 12, 14 are preferably made fromaluminum, but other suitable materials may be used. As shown in FIG. 3,the rear slide rails 12 have a flat bottom portion 36 to slide along theendless track 38 shown in FIG. 12, for example. Conventionally, the flatbottom portion 36 is covered with a nylon slide, (not shown) to decreasethe friction between the rear slide rails 12 and the endless track 38.The rear slide rails 12 also include several apertures 40 to make therear slide rails 12 lighter in weight.

[0048] Rear slide rails 12 may also include extensions 42 where frontstoppers 44 and rear stoppers 46 are preferably mounted. While notrequired to practice the present invention, extensions 42 provide aplatform for the front stopper 44 and rear stopper 46. Front and rearstoppers 44 and 46 define the extremes between which a coupledsuspension operates.

[0049] The front slide rails 14, also shown in FIG. 3, are preferablymade from aluminum. Just as with rear slide rails 12, front slide rails14 may include several apertures 40 to lighten the weight thereof. Frontslide rails 14 have a flat bottom portion 48 which is normally coveredby a nylon slide (not shown) to reduce the friction between the frontslide rails 14 and the endless track 38 shown in FIG. 12.

[0050] As illustrated in FIG. 4, the front slide rails 14 are pivotallyattached to the chassis 34 through a linkage 50. The linkage 50 isattached to the chassis 34 near or at the front drive axle 52 shown inFIG. 4. As illustrated, the linkages 50 are elongated plate-like membersthat pivotally connect between the chassis 34 and the front slide rails14. Preferably, linkages 50 are fabricated from aluminum because of itslow weight. However, any suitable material may be used.

[0051] In the preferred embodiment illustrated in FIG. 7, the frontslide rails 14 are pivotally attached directly to the chassis 34 withoutlinkages 50.

[0052] A third embodiment, illustrated in FIG. 13 shows the front rails14 connected to the chassis 34 via the front drive axle 52. FIG. 13shows linkage 50 connecting the front slide rail 14 to the front driveaxle 52, but front rails 14 could be directly connected to the frontdrive axle 52 via its front end 32 as indicated in FIG. 14.

[0053] One type of pivot point 26, shown in further detail in FIGS. 8and 9, is a bushing-type pivot, but other methods of attachment areavailable. The pivot point 26 comprises a bushing 72, a spacer 74, andseveral washers 76 all held together with a nut 80 and bolt 82. Theforward end 28 of the rear slide rails 12 includes an extended portion90, which has a hole 86 passing therethrough. The extended portion 90contacts the surface of the spacer 74 which in turn contacts the surfaceof an extended portion 92 of the associated front slide rail 14.Extended portion 92 also has a hole 96 passing therethrough. As depictedin FIG. 9, flanges 88 extend from the flat bottom portion 36 of the rearslide rails 12. Similar flanges 94 extend from the flat bottom portion48 of the front slide rails 14. Preferably these components are madefrom aluminum or plastic, but other materials may be suitable therefor.

[0054] A second and preferable type of pivot connection between thefront slide rails 14 and the rear slide rails 12 is shown in detail inFIG. 10. FIG. 10 shows each pair of slide rails 12 and 14 connected witha pivot plate 106. Pivot plate 106 has a first end 112 and a second end114. Preferably, pivot plate 106 is attached to the front slide rails 14at the first end 112 by two fasteners 110 to prevent any relativemovement therebetween. Fasteners 110 can be for example, nut and bolttype fasteners, rivets or any suitable attachment means which willwithstand the shocks transferred from the rough terrain which asnowmobile encounters. The second end 114 of the pivot plate 106 isrotatably connected to a shaft 108. Pivot plate 106 has passing throughthe second end 114 a hole 116 through which shaft 108 passes.Preferably, hole 116 contains a ball bearing or journal bearing toreduce the friction between the pivot plate 106 and the shaft 108.

[0055] The forward end 28 of the rear slide rails 12 also have passingtherethrough a hole 118 to accept shaft 108. As with hole 116, hole 118may be fitted with friction reducers such as ball bearings. As shown inFIG. 10, shaft 108 extends from the left slide rail 18 across to rightslide rail 16. Shaft 108 helps to increase the rigidity of the sliderail system as well as providing a rotational support for idler wheels120. Although the preferred embodiment has the pivot plate 106 fixedlyattached to the front slide rails and pivotally attached to the rearslides via shaft 108, it is possible to invert the connection and fixthe pivot plate 106 with the rear slide rails 12 and pivotally connectthe pivot plate 106 with the front slide rails 14 via the shaft 108.

[0056]FIG. 11 shows a pivot connection between front slide rails 14 andthe chassis 34. The forward portions 32 of the front slide rails 14 eachhave a hole 124 passing therethrough to accept a tube 122. Tube 122extends laterally between the two sides of the chassis 34. Tube 122 isconnected to the front slide rails 14 by a triangular flange 126 that isfixedly connected to the tube preferably by fasteners or welding.Triangular flange 126 is also connected to the front slide rails 14 toprevent relative movement between the front slide rails 14 and the tube122. A rod 128 passes through tube 122 such that rod 128 can rotatewithin the tube 122. The rod 128 is attached to the chassis 34,preferably by bolts 130, to prevent relative movement between thechassis 34 and the rod 128. It would be recognized that the length ofrod 128 to be slightly longer than tube 122 to allow rotation of tube122 about rod 128 when bolts 130 secure rod 128 to the chassis 34. Therod 128 may carry friction reducers such as ball bearings or journalbearings. Tube 122 may also carry a mechanism that introduceslubrication between the contacting surfaces of tube 122 and rod 128.

[0057]FIG. 14 shows a pivot connection between the front slide rails 14and the front drive axle 52. In the connection shown in FIG. 14, theforward portion 32 of the front slide rails 14 have holes 132 passingtherethrough to accept the front drive axle 52. Preferably, hole 132would be fitted with friction reducers such as ball bearings or journalbearings. Also shown in FIG. 14 are sprockets 134 attached to the driveaxle 52. Sprockets 134 are used to transfer rotational movement of thedrive axle 52 to rotational movement of the endless track 38.

[0058]FIG. 15 shows an alternate connection between the front sliderails 14 and the front drive axle 52. Attached to the forward portion 32of the front slide rails 14 is a pivot plate 135 similar to pivot plate106. Pivot plate 135 has a first end 136 and a second end 138. The firstend 136 of the pivot plate 135 is attached to the forward portion 32 ofthe front slide rails 14 using bolts 140, but other methods ofattachment are available. The second end 138 of the pivot plate 135 hasa hole 142 passing therethrough to accept the front drive axle 52.Preferably, hole 142 is fitted with friction reducers such as ballbearings or journal bearings. Also shown in FIG. 15 are sprockets 134attached to the front drive axle 52 to transfer rotational movement ofthe front drive axle 52 to the endless track 38.

[0059] The slide rail system of the present invention will now bedescribed in connection with a rear suspension system that connects therear slide rails to the chassis of a snowmobile.

[0060] Shown in FIG. 12 is an adjustable rear suspension system 54 usedfor mounting the endless track 38 to the chassis 34 of snowmobile 70. Asillustrated in greater detail in FIGS. 4 and 5, the suspension system 54comprises the front slide rails 14, rear slide rails 12 and a rearsuspension arm 56. Also mounted to the rear slide rails 12 is aplurality of wheels 58 for engagement with the endless track 38. Atleast two torsion spring-like members 60 are connected to the chassis 34near the rear suspension arm 56 and the rear slide rails 12 to urge therear slide rails 12 away from the chassis 34 so that the suspension isin a ready position to absorb shocks as the vehicle travels over uneventerrain.

[0061] The rear suspension arm 56 has an upper end pivotally connectedto the chassis 34 and a lower end pivotally connected to a pair ofblocks 62 via a cross bar 64. The cross bar 64 is connected to a rockerarm assembly 66 which is, in turn, pivotally connected to the rear sliderails 12.

[0062] A shock absorber 68 has an upper end pivotally connected to therear suspension arm 56 which is in turn connected to the chassis 34 anda lower end pivotally connected the rear slide rails 12 through atransverse rod 24 or other conventional pivot means attached to sliderails 12. A secondary compression spring (not shown) can be added overthe shock absorber 68 to enhance the shock absorbing characteristics ofthe suspension system.

[0063] While the slide rails system 10 of the present invention areshown to support the suspension system of the MX Z TM Ski-Doos byBombardier Inc of Montreal Quebec, Canada (2001 model year), the presentinvention could be supported by other suspension systems and is notlimited thereby. For example, the suspension system described in U.S.Pat. No. 5,904,216 could be substituted for the suspension 54illustrated in FIGS. 4 and 5. Another example of a rear suspensionsystem that could be supported by the slide rail system 10 of thepresent invention is described in U.S. Pat. No. 5,265,692, incorporatedherein by reference.

[0064] Referring to FIG. 12, the slide rail system 10 may be used on anysuitable vehicle, including a snowmobile 70. Snowmobile 70 has a chassis34 on which an engine 104 is disposed. Chassis 34 has an invertedU-shaped cross section through which an endless track 38 rotates. A pairof skis 100 is attached to the front portion of the chassis 34 and isconnected to a steering device 102 to steer the snowmobile 70. Theendless track 38, connected to the engine 104, is placed under thechassis 34 to propel the snowmobile 70. The snowmobile 70 includes theslide rail system 10 described above.

[0065]FIG. 16 illustrates a mechanism 400 that prevents the freerotation of the rocker arm assembly 66. Mechanism 400 could be aconventional shock absorber for example or a specific type of cylinderthat would create resistance to clockwise and counterclockwise rotationof the rocker arm assembly 66. Shown in FIG. 16, mechanism 400 isattached to the rear slide rails 12 via a bar 402 which is fixedlyattached to each rear slide rail 12 at points 404 and 406. Theattachment point 408 between the mechanism 400 and the bar 402 ispreferably a rotating attachment point in order to permit the mechanism400 to rotate about the rear slide rails 12 when the suspension systemis compressed. A second end 410 of the mechanism 400 is attached to thecross bar 64 connecting the arms of the rocker arm assembly 66. Themechanism 400 may be attached directly to the rocker arm assembly 66.The second end 410 of the mechanism 400 is preferably rotatably attachedto the cross bar 64 to permit rotation therebetween. Although shown inFIG. 16 in combination with the second embodiment having the front sliderails 14 attached directly to the chassis 34, that mechanism 400 mayalso be installed with the embodiments shown in FIGS. 3 and 13.

[0066]FIG. 17 shows a side view of the preferred embodiment of themechanism 400. Mechanism 400 includes a rod 420 on which a piston 422 isattached such that there is no relative movement therebetween. Enclosingthe piston 422 and a portion of the rod 422 is a body 424. Preferably,body 424 comprises a cylindrical hollow tube with sealed end portionsthrough which the rod 420 passes such that the rod 422 can push and pullthe piston 422 within the body 424. A first end 426 of rod 422 isattached to the cross bar 64 at point 410 as explained above. In orderto prevent damage to the body 424 in the event of counterclockwiserotation of the rocker arm assembly 66 far enough to cause contactbetween the body 424 and the cross bar 64, a rubber bumper 428 isinstalled on the rod 422 near the connection point 410 of the first end426 of the rod 420 and the cross bar 64.

[0067] An adjustment 450 may be placed between the cross bar 64 and therubber bumper 428 to limit the counterclockwise movement of the rockerarm 66. The adjustment 450 could be a nut threadedly engaging the rod420 moveable longitudinally along the rod 420 to alter the position ofthe rubber bumper 428. Preferably, adjustment 450 would be placed behindthe rubber bumper 428 to avoid contact with the body 424, but as oneskilled in the art would recognize, the adjuster and the bumper could beone single part moveable longitudinal along rod 420.

[0068] Piston 422 sealing engages the interior of the body 424. Piston422 also includes one or more channels 430 passing longitudinallythrough the piston 422. Preferably, body 424 is filled with hydraulicoil to create resistance to the piston during relative movement betweenthe piston 422 and the body 424. In order to ensure that no oil leaksfrom the body 424, the inlet 432 and the outlet 434 of the rod 420 withthe body 424 are preferably sealed with rubber rings or any other seals.

[0069] Piston 422 also carries one or more valves 442. Valve 442 createsresistance to the oil passing through channels 430. By adding orremoving the valves, the damping characteristics of the mechanism 400can be altered to suit any desired working condition.

[0070] The second end 436 of the rod 420 includes an adjustment 440. Inthe preferred embodiment the adjustment 440 is a nut which is threadedlyengaged with the second end 436 of the rod 420. The adjustment 440allows the amount of rod 420 entering the outlet 434 to be adjusted.This in turns limits the amount of clockwise rotation of the rocker armassembly 66. In order to prevent damage to the body 420 in the event ofcontact between the adjustment 440 and the body 424, a rubber bumper 438is placed on the rod 420 between the adjustment 440 and the body 424.Although the preferred embodiment is shown as having on single rod 420,two rods could be used having a common attachment point at the piston422, for example.

[0071] Mechanism 400 also includes a housing 444. Housing 444 isattached to the body 424 at a first end 446 and to the rear slide rails12 at a second end 448. Preferably, housing 444 is welded or threaded tothe body 424 but as one skilled in the art would recognize, othermethods of attachment are available. Housing 444 is preferably shaped toinclude a window 450 through which access to the adjustment 440 ispermitted. This permits the user to adjust certain characteristics ofthe mechanism 400 without removal of the mechanism 400 from the rearslide rails and the cross bar 64. The second end 448 of the housing 444is rotatably attached to the transverse bar 402 at point 408 as shown inFIG. 16 and described above.

[0072] During rotation of the rocker arm assembly 66, the rod 420 willmove the piston 422 relative to the body 424 and cause the piston 422 totravel through the oil. The channels 430 therefor restrict or reduce thespeed at which the rocker arm assembly 66 can rotate with respect to theslide rails 12. The valves 442 create additional restriction of the oilthrough the channels 430 and can be added or removed as needed.

[0073] The length of the front slide rails 14 and the rear slide rails12 within the preferred embodiments are measured from the pivot point 26to the end of the corresponding slide rail along the longitudinaldistance of each rail. Although the preferred ratio of lengths betweenthe front slide rails 14 and the rear slide rails 12 lie within therange of 50% to 100%, any combination of lengths may be used dependingon the use of the snowmobile 70 and the riding conditions.

[0074] While the invention has been described with the reference to thevarious disclosed embodiments, it will be understood that variousmodifications may be made without departing from the spirit and scope ofthe invention.

What is claimed is:
 1. A slide rail system suitable for use on a tracked vehicle having a chassis, a front drive axle, and an endless track, the system comprising a pair of substantially spaced-apart parallel elongated slide members, the pair being defined by a first slide member and a second slide member, each slide member having a forward end, a rear end and a bottom portion being suitable for engaging with the endless track; the forward end of each slide member suitable for connection to at least one of the chassis of the tracked vehicle and the front drive axle of the tracked vehicle via a linkage.
 2. The slide rail system of claim 1, wherein each slide member comprises a front slide rail and a rear slide rail, each rail having a forward end, a rear end and a bottom portion suitable for engaging the endless track; the forward end of the rear slide rail of the first slide member being pivotally connected to the rear end of the front slide rail of the first slide member; and the forward end of the rear slide rail of the second slide member being pivotally connected to the rear end of the front slide rail of the second slide member.
 3. The slide rail system of claim 2, wherein each slide rail has a length, and a ratio of the length of each front slide rail to the length of each rear slide rail is in a range of 50% to 100%.
 4. The slide rail system of claim 2, wherein the linkage further comprising a first linkage and a second linkage, each linkage having a first end and a second end; and wherein the forward end of the front slide rail of the first slide member is attached to the first end of the first linkage; the forward end of the front slide rail of the second slide member is attached to the first end of the second linkage; and the second end of each linkage is suitable for attachment to one of the front drive axle of the tacked vehicle and the chassis of the tracked vehicle.
 5. The slide rail system of claim 4, wherein the forward end of the front slide rail of the first slide member is pivotally attached to the first end of the first linkage; and the forward end of the front slide rail of the second slide member is pivotally attached to the first end of the second linkage.
 6. A snowmobile, comprising: a chassis; an engine disposed on the chassis; at least one ski disposed on the chassis; a steering column operatively connected to the at least one ski for steering the snowmobile; an endless track disposed below the chassis and being operatively connected to the engine via a front drive axle for propelling the snowmobile; and a pair of substantially parallel elongated slide members, each slide member having a forward end, a rear end and a bottom portion engaging the endless track, the forward end of each slide member being suitable for connection to at least one of the chassis of the tracked vehicle and the front drive axle of the tracked vehicle via a linkage.
 7. The snowmobile of claim 6, wherein each slide member comprises a front slide rail and a rear slide rail, each rail having a forward end, a rear end and a bottom portion suitable for engaging the endless track; the forward end of the rear slide rail of the first slide member being pivotally connected to the rear end of the front slide rail of the first slide member; and the forward end of the rear slide rail of the second slide member being pivotally connected to the rear end of the front slide rail of the second slide member.
 8. The snowmobile of claim 7, wherein each slide rail has a length, and a ratio of the length of each front slide rail to the length of each rear slide rail is in a range of 50% to 100%.
 9. The snowmobile of claim 7, wherein the linkage further comprising a first linkage and a second linkage, each linkage having a first end and a second end; and wherein the forward end of the front slide rail of the first slide member is attached to the first end of the first linkage; the forward end of the front slide rail of the second slide member is attached to the first end of the second linkage; and the second end of each linkage is suitable for attachment to one of the front drive axle of the tracked vehicle and the chassis of the tracked vehicle.
 10. The snowmobile of claim 9, wherein the forward end of the front slide rail of the first slide member is pivotally attached to the first end of the first linkage; and the forward end of the front slide rail of the second slide member is pivotally attached to the first end of the second linkage.
 11. A snowmobile, comprising: a chassis; an engine disposed on the chassis; at least one ski disposed on the chassis; a steering column operatively connected to the at least one ski for steering the snowmobile; an endless track disposed below the chassis and being operatively connected to the engine via a front drive axle for propelling the snowmobile; a pair of substantially parallel elongated slide members, each slide member having a forward end, a rear end and a bottom portion engaging the endless track; a rear suspension arm having a first end pivotally connected to the chassis and a second end pivotally connected to the rear slide rails; and an hydraulic mechanism having a first end connected to the rear suspension arm and a second end connected to the slide rails, wherein the hydraulic mechanism controls the rate at which the rear suspension arm rotates with respect to the slide rail. 